Digital or Free Form?

I can not think of any other terms in our business that have created so much confusion than these! I just read an EXCELLENT article in this months EyeCare Professional Magazine that clears up the confusion very effectively!

I think that this will be very beneficial to those ECPs who are more and more confused as the BigBoy Optical spin these terms in ever twisted ways! Do yourself, your staff, our business a favor and read this optical gem!

http://www.ecpmag.com/1webmagazine/2...orm-lenses.asp

I want to thank the author for this fantastic article and I think it will be a HUGE help to those who are still confused!

Thanks for the article :smile:.

AFAIK:
CNC -> Computer numerically controlled machining: the surface geometry is represented as numerical coordinates, fed to the machine.
Single-point diamond turning -> self explanatory (https://en.wikipedia.org/wiki/Single...iamond_turning).

"Free-Form": A surface is described by many closely fit x,y,z coordinate points and all the points are collected in a file. This file is fed to a CNC single point cutter, which generates the surface described by the points file.

Free-Form = CNC single-point diamond turning.

Any surface can be described by multiple x,y,z coordinate points ... even the face of Micki Mouse can be Free-Form machined onto a surface.
You can manufacture a spherical surface with a Free-Form manufacturing process ... just feed the points file describing the surface.

This manufacturing technique does not require patterns or moulds to be prepared in advance.
The machine takes the puck of material and the coordinate points file and creates the described surface.
This is "Free-Form".

Now we have powerfull computers .. which can calculate an optical surface and describe it as a series of x,y,z coordinate points in no time.
If you can imagine (design) a surface the Free-Form machine can create it.

Someone can design this*:
http://musee.louvre.fr/oal/psyche/img/fond01_02.jpg

While someone else can design this:
http://www.jaxie.nl/cms/images/stori...sova-crea2.jpg

Both can be made with Free-Form machining and later be truthfully called "Free-Form".

*the statue:
Antonio CANOVA (1757 – 1822)
Psyche Revived by Cupid’s Kiss

The CNC machines have been around for a long time. What makes the Free form possible is the software portion of the process (taking a pts. Rx and converting it to a surface that describes the Rx), which I have no idea how long that has been around. The CNC machines are nearly as good as they are going to get (with in reason), but the software will continue to evolve and so will lenses materials and coatings.

Digital 3-axis generators have been around for what, 40 years? New polishing and generating methods along with sophisticated electronics make it possible to create more complex surfaces, free-form if you wish, but as you can see from Nikolay's pictures above, complex isn't always better.

I tell my clients that the fundamental PAL design that I use for each individual is selected to match their Rx and visual needs, and that further optimizing (Rx and POW) has the potential (more so with certain Rxs and fitting parameters) to slightly improve their visual comfort and acuity.

Dupe deleted

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Originally Posted by Robert Martellaro

I tell my clients that the fundamental PAL design that I use for each individual is selected to match their Rx and visual needs, and that further optimizing (Rx and POW) has the potential (more so with certain Rxs and fitting parameters) to slightly improve their visual comfort and acuity.

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We say that it will likely improve their visual comfort and acuity and has the potential to dramatically improve it. In fact, we hear this quite often.

"Free Form is a manufacturing process, not a lens design." ~Darryl Meister

To illustrate Darryl's point, let's look at the Varilux "Free Form" family.

First, we'll start with a Varilux Physio. Conventional blank, generated on a "conventional" generator, with the usual LMS software determining the back surface curves (usually in 1/8th or 1/10th diopter).

Next, we'll go to the Varilux Physio 360. Same lens blank as a regular Physio, generated on a "Digital" generator, with the curves determined by special software (W.A.V.E technology), usually cut to 1/100th of a diopter.

After that, we'll go to the Varilux Physio Enhanced. Still the same conventional blank, generated on a "Digital" generator, with the curves determined by more advanced software (W.A.V.E technology 2), also to 1/100th of a diopter.

Finally we go to the Varilux Physio DRx. Spherical front surface blank, with the Physio lens design on the back surface of the lens. Again, on a "Digital" generator, again to 1/100th of a diopter.

Three of the four are considered (by some) to be Free Form, but all four use the SAME progressive design (Physio). The only difference is curve accuracy on the 360 and Enhanced, and putting the Physio design on the back surface instead of the front (DRx).

I order to fully take advantage of what the Free Form process can do, the design should change as needed based on Rx, patient measurements (PD, Seg ht), frame shape, and POW measurements. Static designs on the back surface will provide an improvement to patient vision, though how noticable of an improvement will obviously vary.

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Originally Posted by WFruit

"Free Form is a manufacturing process, not a lens design." ~Darryl Meister

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Interesting discussion in semantics. To me, free form is just someones slang for describing the entire process - the advanced mathematics and physics that get applied, resulting in the end to describe a surface of an advanced lense which attempts to achieve perfect Rx. Comprehensive pts measurements are input into the software and out comes a roadmap to build a perfect Rx at all viewing angles and will somehow be manufactured. Who knows, someday they may not use CNC machines to build it. I could be convinced to argue that free form is applied bio-mechanical physics, not a manufacturing process.

I'm curious to know what you may think about the newer Varilux Enhanced Fit or the Varilux SD 4d lenses our office recently received the essilor Visio-Office and only a small percentage of the patients we have fit have enjoyed a substantial improvement in there perception through these lenses. In fact, each of the opticians in our office that have tried it do not have the confidence to sell it because of there own personal experience with the lenses. These opticians went back into their physios or even their Definity lenses.

Thanks for your input.

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Originally Posted by nate2140

I'm curious to know what you may think about the newer Varilux Enhanced Fit or the Varilux SD 4d lenses our office recently received the essilor Visio-Office and only a small percentage of the patients we have fit have enjoyed a substantial improvement in there perception through these lenses. In fact, each of the opticians in our office that have tried it do not have the confidence to sell it because of there own personal experience with the lenses. These opticians went back into their physios or even their Definity lenses.

Thanks for your input.

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It's always a comparative and multi-layered, including Rx delta and neural adaptation.

Barry

Quote:

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Originally Posted by nate2140

I'm curious to know what you may think about the newer Varilux Enhanced Fit or the Varilux SD 4d lenses our office recently received the essilor Visio-Office and only a small percentage of the patients we have fit have enjoyed a substantial improvement in there perception through these lenses. In fact, each of the opticians in our office that have tried it do not have the confidence to sell it because of there own personal experience with the lenses. These opticians went back into their physios or even their Definity lenses.

Thanks for your input.

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Think I've seen this particular lens discussed in another thread. You may want to search around for better results and also to keep with the thread topic. Many people may not respond to your question due to the thread title. 1st things first, you need to learn how to use the Visi-Office. When you are convinced you are using it properly, then you can reduce that variable in your judgement of the lens design. Your experience is not what I've seen elsewhere, so I'd go back to the drawing board before giving up.